How Solar Panels Turn Sunlight Into Electricity
Individual solar cells can vary from 0.5 inches to about 4.0 inches across. Some of them can convert artificial light, as well as sunlight, into electricity.
A photovoltaic (PV) cell, commonly called a solar cell, converts sunlight directly into electricity. When its semiconductor material absorbs enough sunlight, electrons are dislodged from the material’s atoms. Cells are connected in panels and panels in arrays, and inverters convert the cells’ direct current (DC) to alternating current (AC).
How a Solar Cell Turns Sunlight Into Electricity
The U.S. Energy Information Administration (EIA) describes a PV cell as a nonmechanical device that converts sunlight directly into electricity. Sunlight is composed of photons, or particles of solar energy. The cell itself is made of semiconductor material.
A photon that strikes a PV cell meets one of three fates: it reflects off the cell, passes through it, or is absorbed by the semiconductor material. Only the absorbed photons provide energy to generate electricity.
When the semiconductor material absorbs enough sunlight, electrons are dislodged from the material’s atoms. Special treatment of the cell’s surface during manufacturing makes the front surface more receptive to those dislodged, or free, electrons, and the electrons naturally migrate to the surface of the cell.
That migration toward the front creates an imbalance of electrical charge between the cell’s front and back surfaces. The imbalance creates a voltage potential similar to the negative and positive terminals of a battery.
Electrical conductors on the cell absorb the electrons. When those conductors are connected in an electrical circuit to an external load, such as a battery, electricity flows through the circuit.
The U.S. Department of Energy (DOE) states that a PV cell contains a semiconductor material that can absorb sunlight and convert it to electricity. Exposed to sunlight, the semiconductor absorbs the light’s energy and transfers it to negatively charged particles in the material called electrons. That extra energy lets the electrons flow through the material as an electrical current.
The current leaves the cell through conductive metal contacts, which are the grid-like lines on a solar cell. Silicon is, by far, the most common semiconductor material used in solar cells.
From a Single Cell to a Rooftop Array
The EIA calls the PV cell the basic building block of a PV system. One PV cell can only produce 1 or 2 Watts. That is only enough electricity for small uses, such as powering calculators or wristwatches.
Larger solar cells are grouped to form PV panels. The cells are electrically connected in a packaged, weather-tight panel, which is sometimes called a module.
PV panels vary in size and in the amount of electricity they can produce. Generating capacity rises with the number of cells in the panel or with the panel’s surface area.
Panels, in turn, can be connected in groups to form a PV array. An array can have as few as two PV panels or as many as hundreds. Arrays can produce electricity for an entire house, and the number of panels in an array determines how much electricity it can generate.
Some PV power plants have large arrays that cover many acres and generate electricity for thousands of homes. Utility-scale power plants have at least 1,000 kilowatts (kW), or one megawatt (MW), of generation capacity.
Small-scale PV systems have less than 1,000 kilowatts of generation capacity. Most of them are located on buildings, and they are sometimes called rooftop PV systems.
In 2025, utility-scale PV power plants accounted for about 76% of total solar electricity generation. Small-scale PV systems accounted for about 24% of total solar electricity generation in 2025.
Direct Current, Inverters, and the Grid
PV cells generate DC electricity, the EIA states. Nearly all electricity is supplied as AC in transmission and distribution systems. Devices called inverters are used on PV panels or in PV arrays to convert the DC electricity to AC.
The DOE describes an inverter as a device that converts DC electricity to AC electricity. DC is what a solar panel generates. AC is what the electrical grid uses.
In DC, electricity is maintained at constant voltage in one direction. In AC, electricity flows in both directions in the circuit as the voltage changes from positive to negative.
An inverter manages that conversion by switching the direction of a DC input back and forth very rapidly.
In a large-scale utility plant or a mid-scale community solar project, every solar panel might be attached to a single central inverter. String inverters connect a set of panels, a string, to one inverter. That inverter converts the power produced by the entire string to AC.
Microinverters are smaller inverters placed on every panel.
Since 2004, most PV systems in the United States are grid-connected, according to the EIA.
What the Output Depends On
The amount of available sunlight depends on the time of day, location, season, and weather conditions, the EIA states. Capturing enough energy to be useful takes a large surface area.
Availability and intensity of solar radiation at the earth’s surface vary by time of day and by location. Buildings, trees, and mountains may shade a spot at different hours and in different months of the year.
PV cells and panels produce the most electricity when they are directly facing the sun. At the earth’s surface, solar energy is a variable and intermittent energy source.
The amount of electricity produced from PV cells depends on the characteristics of the light, such as intensity and wavelength, the DOE states. It also depends on performance attributes of the cell. The conversion efficiency of a PV cell is the percentage of the solar energy shining on a PV device that is converted into usable electricity.
Not all of the sunlight reaching a cell becomes electricity. Most of it does not. Some of the absorbed photons have their energy turned into heat instead.
Untreated silicon reflects more than 30% of incident light. Anti-reflection coatings and textured surfaces help decrease that reflection.
Sources: U.S. Energy Information Administration; U.S. Department of Energy
| What changes | Effect | Applies to |
|---|---|---|
| The sun’s position in the sky | In general, the intensity of solar radiation at any location is greatest when the sun is at its highest apparent position in the sky, at solar noon, on clear, cloudless days. | Sunlight reaching the surface |
| Latitude and climate | Locations in lower latitudes and in arid climates generally receive higher amounts of insolation than other locations. | Sunlight reaching the surface |
| Distance from the equator | Seasonal (monthly) variations in solar resources increase with increasing distance from the earth’s equator. | Sunlight reaching the surface |
| Clouds, dust, volcanic ash, and pollution | They affect insolation levels at the surface. | Sunlight reaching the surface |
| Which way the panel faces | PV cells and panels produce the most electricity when they are directly facing the sun. | Panel output |
| Cell temperature | Solar cells generally work best at low temperatures. Higher temperatures bring a slight increase in current, but a much larger decrease in voltage. | The cell |
| Shade on one panel, string inverter | Power production on the string is reduced if any individual panel experiences issues, such as shading. | The whole string |
| Shade on one panel, microinverter | Shading to one panel will not affect the power that can be drawn from the others. | The other panels |
Insolation is the amount of solar radiation received on a given surface area during a specific amount of time.
After Sunset and During Grid Disruptions
The EIA states that PV systems can also charge a battery. That battery can then provide electricity when the sun is not shining, for individual devices, single homes, or electric power grids.
The DOE gives the inverter attached to a household solar system as one example of a small inverter. In general, the standard for small inverters is to remain on during, or ride through, small disruptions in voltage or frequency.
In general, if a disruption lasts for a long time or is larger than normal, these small inverters disconnect from the grid and shut down.
Solar-plus-battery storage systems rely on advanced inverters to operate without any support from the grid in case of outages, if they are designed to do so.
A PV cell turns only part of the sunlight that reaches it into electricity. The amount of sunlight available to it depends on the time of day, location, season, and weather conditions. Inverters turn the cells’ direct current into the alternating current the grid uses.